Wafer based corrosion and time dependent chemical effects

ABSTRACT

Embodiments may also include a residual chemical reaction diagnostic device. The residual chemical reaction diagnostic device may include a substrate and a residual chemical reaction sensor formed on the substrate. In an embodiment, the residual chemical reaction sensor provides electrical outputs in response to the presence of residual chemical reactions. In an embodiment, the substrate is a device substrate, and the sensor is formed in a scribe line of the device substrate. In an alternative embodiment, the substrate is a process development substrate. In some embodiments, the residual chemical reaction sensor includes, a first probe pad, wherein a plurality of first arms extend out from the first probe pad, and a second probe pad, wherein a plurality of second arms extend out from the second probe pad and are interdigitated with the first arms.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.15/480,337, filed on Apr. 5, 2017, the entire contents of which arehereby incorporated by reference herein.

BACKGROUND 1) Field

Embodiments relate to the field of semiconductor manufacturing and, inparticular, to systems and methods for providing real time monitoring ofresidual reactions on a substrate after a processing operation has beenimplemented.

2) Description of Related Art

Subsequent to some processing operations in semiconductor manufacturing,there may be residual chemical reactions that persist on the substrate.These residual chemical reactions may adversely affect the performanceof a semiconductor device. For example, residual chemical reactions mayresult in corrosion, changes in the properties of the film, or defects.Conversely, some deposited films may require chemical conversion postdeposition to a final state prior to subsequent processing operations.However, the residual chemical reaction that is occurring postprocessing may not always be well understood. For example, the residualchemical reactions may proceed at an unknown rate and/or be dependent onthe conditions in which the semiconductor device is stored, such astemperature, humidity, exposure to gasses in the atmosphere, or thelike. Accordingly, the ability to quantify the results of the chemicalreactions in real time may provide the ability to optimize processconditions to minimize residual chemical reactions and/or optimizeprocess flows and yields.

However, there are no devices currently available that can measure theeffects of the residual chemical reactions in real time. Some techniquesexist to determine these effects, for example, a defect inspectionsystem may be used to determine the increase in defects over time, orthe film thickness may be measured with an ellipsometer to determinedifferences over time. Unfortunately, these measurements requirehandling the semiconductor device and can only provide discretemeasurements over the duration the devices are monitored.

SUMMARY

Embodiments includes systems and methods for determining the presence ofresidual chemical reactions on processed substrates. In an embodiment, amethod for determining the presence of residual chemical reactions, mayinclude forming a sensor on a substrate. In an embodiment, the methodmay further include placing the substrate in a testing chamber. Afterthe substrate is placed in a testing chamber, embodiments may includeexecuting a diagnostic procedure on the substrate where electricaloutputs from the sensor are recorded during the diagnostic procedure.Thereafter, embodiments may include determining a subsequent processingoperation based on the recorded electric outputs from the sensor.

Embodiments may also include methods where the substrate is a processdevelopment substrate and methods where the substrate is a productionsubstrate. According to an embodiment, when the substrate is aproduction substrate, the sensor may be formed in the scribe line of thesubstrate. According to an embodiment, the diagnostic procedure includesmonitoring changes to one or more of a capacitance, a capacitance noisefloor, a charge measurement, a leakage current, a breakdown voltage, anda resistance.

Embodiments may also include a residual chemical reaction diagnosticdevice. The residual chemical reaction diagnostic device may include asubstrate and a residual chemical reaction sensor formed on thesubstrate. In an embodiment, the residual chemical reaction sensorprovides electrical outputs in response to the presence of residualchemical reactions. In an embodiment, the substrate is a devicesubstrate, and the sensor is formed in a scribe line of the devicesubstrate. In an alternative embodiment, the substrate is a processdevelopment substrate. In some embodiments, the residual chemicalreaction sensor includes, a first probe pad, wherein a plurality offirst arms extend out from the first probe pad, and a second probe pad,wherein a plurality of second arms extend out from the second probe padand are interdigitated with the first arms.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a cross-sectional illustration of a patterned stack ofmaterials formed over a substrate, according to an embodiment.

FIG. 1B is a cross-sectional illustration of the patterned stack ofmaterials in FIG. 1A after a residual chemical reaction has changed thedimensions of a trench in the patterned stack of materials, according toan embodiment.

FIG. 1C is a cross-sectional illustration of the patterned stack ofmaterials in FIG. 1A after a residual chemical reaction has resulted inthe formation of nodules along sidewalls of a trench in the patternedstack of materials, according to an embodiment.

FIG. 1D is a cross-sectional illustration of a patterned stack ofmaterials that has residual etch byproducts formed along sidewalls of atrench, according to an embodiment.

FIG. 2A is a plan view illustration of a sensor that may be patternedinto a stack of materials on a substrate, according to an embodiment.

FIG. 2B is a plan view illustration of an alternative sensor that may bepatterned into a stack of materials on a substrate, according to anembodiment.

FIG. 3A is a plan view illustration of process development substratethat includes a plurality of sensors, according to an embodiment.

FIG. 3B is a plan view illustration of a portion of a productionsubstrate that includes a sensor formed in a scribe line, according toan embodiment.

FIG. 4 is a cross-sectional schematic illustration of a testing chamberthat may be used in conjunction with sensors formed on a productionsubstrate or a process development substrate, according to anembodiment.

FIG. 5 is a process flow diagram that describes a process for usingsensors on a production substrate or a process development substrate,according to an embodiment.

FIG. 6 illustrates a block diagram of an exemplary computer system thatmay be used in conjunction with processes that include monitoringresidual chemical reactions, in accordance with an embodiment.

DETAILED DESCRIPTION

Systems and methods for using a structures fabricated onto substrates toprovide monitoring of corrosion and other time dependent chemicalreactions are described in accordance with various embodiments. In thefollowing description, numerous specific details are set forth in orderto provide a thorough understanding of embodiments. It will be apparentto one skilled in the art that embodiments may be practiced withoutthese specific details. In other instances, well-known aspects are notdescribed in detail in order to not unnecessarily obscure embodiments.Furthermore, it is to be understood that the various embodiments shownin the accompanying drawings are illustrative representations and arenot necessarily drawn to scale.

As noted above, residual chemical reaction may adversely affect theprocessing of some devices fabricated with semiconductor processingtechniques. These residual chemical reactions may result in decreasedyields since the entire process is not fully characterized. For example,after a material layer has been patterned (e.g., with an etchingprocess) a residual chemical reaction, such as corrosion, may proceedafter the substrate is removed from the processing chamber. In suchsituations, the corrosion may alter the pattern formed in the materiallayer and result in defects. Accordingly, embodiments described hereinprovide for systems and methods for characterizing these residualchemical reactions.

In one embodiment, the residual chemical reactions are characterizedprior to fabricating active devices. In such embodiments, one or moresensors may be patterned onto a process development substrate. Thesensors may be formed from the same material layer or layers that willbe present on the devices and fabricated with the same processingoperations used to fabricate the devices that are being investigated.Accordingly, the sensors can then be monitored to provide informationthat is directly related to the processing conditions that the deviceswill be exposed to as well. The information can, therefore, be used torefine the processing operations to minimize a residual chemicalreaction or to be used to quantify the residual chemical reaction sothat the effects of the residual chemical reaction can be accounted forin the design of the device.

In an alternative embodiment, the residual chemical reactions may bemonitored in parallel with the production of active devices. Forexample, one or more sensors may be fabricated in a scribe line or anyother area of a production substrate. In order to predict the effect ofthe residual chemical reaction on the active devices, the residualchemical reaction may be accelerated at the sensor location. In someembodiments, the residual chemical reaction may be accelerated byproviding a localized stimulus (e.g., voltage, current, moisture,chemical species, or the like) to the sensor. Accordingly, theaccelerated residual chemical reaction may be monitored to determine ifthe residual chemical reaction will negatively affect the activedevices. In an embodiment, the data obtained from the sensor may then beused to inform decisions on whether to rework the production substrate,scrap the production substrate, initiate an additional processingoperation (e.g., to add a processing operation designed to slow or stopa residual chemical reaction, or the like). As such, the yield of aprocess may be improved since the full process (including residualchemical reactions) may be quantified earlier and with more precision.

Furthermore, it is to be appreciated that sensors formed in accordancewith embodiments described herein do not need as much handling as thedefect inspection systems described above, in addition to providingcontinuous monitoring as opposed to discrete measurements. Particularly,embodiments include forming sensors that receive electrical inputs(e.g., bias voltage, current, or the like) from a probe and provideelectrical signal outputs. For example, the sensors may be designed toprovide outputs, such as capacitance, resistance, breakdown voltage,current leakage, noise levels, or the like. These outputs may becontinuously recorded, and changes to the outputs over time may be usedto determine the presence and extent of one or more residual chemicalreactions, as will be described in greater detail below. Additionally,environmental condition may also be controlled to further quantifyresidual chemical reactions and/or to determine conditions that reduceor eliminate the residual chemical reactions.

Referring now to FIGS. 1A-1D, exemplary illustrations of the effect ofresidual chemical reactions on a material stack after it has beenprocessed is shown, according to an embodiment. In FIG. 1A, across-sectional illustration of a device 100 after it has been processedis shown, according to an embodiment. The device 100 includes a materialstack 120 that has been patterned, (e.g., with an etching process) toform a trench 125 through the material stack 120. In the illustratedembodiment, the material stack 120 is shown as a single material layerformed over a substrate 105. However, embodiments may include a materialstack 120 that includes one or more material layers formed with one ormore different materials. According to an embodiment, the materiallayers may include metals, semiconductors, composite dielectrics,insulators, organic layers, or any other material. In an embodiment, thesubstrate 105 may be any suitable substrate, such as a semiconductorsubstrate (e.g., silicon, or a III-V semiconductor), a glass substrate,a sapphire substrate, or any other material. In some embodiments,substrate 105 may include multiple layers, such as a silicon oninsulator (SOI) substrate.

In an embodiment, the trench 125 is defined by sidewall surfaces 126 ofthe material stack 120. In an embodiment, the semiconductor device 100is processed so that the sidewalls 126 are spaced apart from each otherby a distance D. However, as described above, residual chemicalreactions that continue after a processing operation is completed maycontinue to alter material stack 120. For example, a residual chemicalreaction may include corrosion which continues to alter the materialstack 120. As shown in FIG. 1B, the sidewalls 126 may be spaced apartfrom each other by a distance D′ that is greater than the distance Dafter the residual chemical reactions have continued for some period oftime. Accordingly, the residual chemical reaction may alter thestructure of the device. In some instances, this change results indeteriorated functionality, or may even result in non-functioningdevices. The ability to accurately predict the result such of residualchemical reactions over a period of time under given conditions and/orreduce the effects of the residual chemical reactions provides theability to account for known changes after processing and improveoverall process control.

It is to be appreciated that residual chemical reactions may not alterthe surfaces of a material uniformly. For example, the residual chemicalreaction may also be localized and not produce a uniform alteration tothe material stack 120 similar to what is illustrated in FIG. 1B. Forexample, corrosion may be a localized reaction and result in pitting orthe formation of nodules on a surface. Such an embodiment is illustratedin FIG. 1C. As illustrated, the sidewalls 126 of the patterned materialstack 120 have developed a plurality of nodules 127. Due to thelocalized nature of the nodule formation, it may not be evident thatthere is a distinct change in the spacing between the sidewalls 126.However, as described in greater detail below, sensors formed inaccordance with embodiments described herein may utilize changes inelectrical properties caused by nodules to determine the existence ofresidual chemical reactions.

Additionally, it is to be appreciated that patterning processes, such asetching, may also leave behind residual etch byproducts. Typically,these byproducts may be comprised of polymer materials. An example ofsuch residual etch byproducts is illustrated in FIG. 1D. In theillustrated embodiment, a polymer layer 129 may be formed along thesidewalls 126 of the patterned material stack 120. Polymer layers 129are typically more susceptible to absorbing moisture or other molecules,burning off at elevated temperatures, or being modified in manydifferent environments. Additionally, as the polymer layers 129 aremodified, changes to electrical properties of the material stack 120 mayalso be observed with sensors formed in accordance with embodimentsdescribed herein. Accordingly, these changes may yield false positives.As such, embodiments include processes for identifying when sensorreadings are indicative of changes to the residual etch byproductsinstead of residual chemical reactions.

Referring now to FIGS. 2A and 2B, plan view illustrations of exemplarysensors 250 that may be used to monitor residual chemical reactions areshown, according to various embodiments. In an embodiment, the sensors250 may be patterned from a material stack, similar to the materialstacks described above with respect to FIGS. 1A-1D. In an embodiment,the material stack used to form the sensors 250 may be the same materialstack that is being investigated. Additionally, the processingoperations used to pattern the material stack may be the same processingoperations used to pattern devices. As such, any residual chemicalreactions that are detected by the sensor will be substantially similarto residual chemical reactions that are present during the production ofactive devices.

Referring now to FIG. 2A, a plan view illustration of an exemplarysensor 250 that may be used to monitor residual reactions is shown,according to an embodiment. Sensor 250 may include a first probe pad2521 and a second probe pad 2522. The probe pads 252 may be sized sothat an external probe can be placed in contact with the sensor 250. Inan embodiment, a plurality of first arms 2541 may extend from the firstprobe pad 2521 and a plurality of second arms 2542 may extend from thesecond probe pad 2522. The first arms 2541 and the second arms 2542 maybe interdigitated with each other so that each arm 254 is separated fromeach a neighboring arm 254 by a distance D. The interdigitated armsallow for a capacitance to build in the sensor 250 when probes are usedto apply current to the probe pads. It is to be appreciated that thestructure of sensor 250 illustrated in FIG. 2A is exemplary in natureand embodiments may include sensors 250 with any number ofinterdigitated arms and with any desired dimensions depending on sizeconstraints and the needs of the device.

Embodiments may include monitoring different electrical properties ofthe sensor 250 in order to detect residual chemical reactions. Forexample, changes to the capacitance of the sensor 250 may be caused byresidual chemical reactions. Generally, a change to the capacitance ofthe sensor 250 may be caused by an increase or decrease in the distanceD between the interdigitated arms 254. For example, the distance Dbetween the interdigitated arms 254 may be caused by corrosion orresidual etching. Additionally, a change in the breakdown voltage of thesensor 250 may be monitored. In some embodiments, the breakdown voltagemay be altered by a change in the distance D or by the formation ofnodules, such as those described with respect to FIG. 1C. While a fewexemplary illustrations of how sensor 250 may be used to identifyresidual chemical reactions are provided here, a more thoroughexplanation of how the sensor may be used is provided in greater detailbelow.

Referring now to FIG. 2B, a sensor 250 according to an additionalembodiment is shown. In FIG. 2B the sensor 250 may include two probepads 252 that are electrically connected together by a trace 255. In anembodiment, the trace 255 may be any desired length or width, and followany desired path between the probe pads 252. In the illustratedembodiment, the traces 255 includes a switchback pattern, thoughembodiments are not limited to such designs. A sensor 250 such as theone illustrated in FIG. 2B may be used to monitor changes to theresistance between the probe pads 252 in order to identify residualchemical reactions. For example, absorption or emission of differentmolecules may alter the resistance of the sensor 250.

Referring now to FIGS. 3A and 3B, schematic illustrations show examplesof where sensors 250 may be fabricated. In FIG. 3A, a plurality ofsensors 250 are fabricated on a process development substrate 320. Thesensors 250 are illustrated schematically as blocks, to indicate thatany suitable sensor formed in accordance with embodiments may be used.The plurality of sensors 250 may be formed at multiple locations overthe surface of a process development substrate 320. For example, thesensors may be formed proximate to the edge of the substrate 320 and/orproximate to a center of the substrate 320 in order to determine ifthere are differences in the residual chemical reactions at differentlocations across the substrate. Since there are no active devices beingfabricated on a process development substrate 320, the sensors 250 arenot restricted from being formed over any portion of the substrate. Inthe illustrated embodiment, seven sensors 250 are shown on the substrate320, but it is to be appreciated that any number of sensors 250 (e.g.,one or more sensors 250) may be formed on the substrate 320, accordingto an embodiment.

Referring now to FIG. 3B, a plan view schematic of a portion of aproduction substrate 321 is shown, according to an embodiment. Theproduction substrate 321 may include a plurality of device regions 329where the active devices may be fabricated. The device regions 329 maybe separated from each other by scribe lines 328, as is known in theart. Embodiments may utilize the space in the scribe lines 328 tofabricate one or more sensors 250. Accordingly, sensors 250 fordetermining the presence of residual chemical reactions may be includedin areas of a production substrate 321 that would otherwise not be usedfor producing functioning devices.

According to an embodiment, sensors 250 formed on production substrates321 or process development substrates 320 may be monitored in a testingchamber. A schematic of a testing chamber 410 is illustrated in FIG. 4,according to an embodiment. In an embodiment, the testing chamber 410may include an enclosure 412. The enclosure 412 may be substantiallysealed in order to maintain desired environmental conditions. While notshown, the test conditions within the enclosure may be obtained bysupplying gases, moistures, or fluids to the enclosure or changing thepressure within the enclosure. In an embodiment, the enclosure 412 mayinclude windows through which electromagnetic radiation of a desiredfrequency may pass or a source of electromagnetic radiation may beincluded within the enclosure 412.

In an embodiment, the testing chamber 410 may include a plate 414 onwhich a substrate 320 and/or 321 may be placed. In an embodiment, theplate 414 may include heating and/or cooling elements in order tocontrol a temperature of the substrate 320 and/or 321 during thetesting. According to an embodiment, the plate 414 may includeelectronics (not shown) that are attached to probes 418. The probes 418are able to contact the probe pads of the sensors formed on thesubstrate 320/321. In the illustrated embodiment, a single set of probes418 are shown contacting the substrate 320/321, but it is to beappreciated that any number of probes 418 may be used to contact aplurality of sensors on a single substrate 320/321. In an additionalembodiment, the testing chamber 410 may accommodate a plurality ofsubstrates 320/321.

Referring now to FIG. 5, a process flow 590 for using sensors formed inaccordance with embodiments described herein is shown. It is to beappreciated that sensors formed in accordance with embodiments describedherein and used in accordance with process flow 590 do not need as muchhandling as the defect inspection systems described above. Additionallyprocess flow 590 allows for continuous monitoring as opposed to discretemeasurements. Particularly, embodiments include forming sensors thatreceive electrical inputs (e.g., bias voltage, current, or the like)from a probe and provide electrical signal outputs. For example, thesensors may be designed to provide outputs, such as capacitance,resistance, breakdown voltage, current leakage, noise levels, or thelike. These outputs may be continuously recorded, and changes to theoutputs over time may be used to determine the presence and extent ofone or more residual chemical reactions. Additionally, environmentalcondition may also be controlled to further quantify residual chemicalreactions and/or to determine conditions that reduce or eliminate theresidual chemical reactions. In an embodiment, the process flow 590 maybe used in conjunction with sensors 250 formed on production substrates321 or for sensors formed on process development substrates 320.

According to an embodiment, the process may begin with operation 591which includes forming a sensor 250 on a substrate. In an embodiment,the sensor 250 may be formed on a production substrate 321 or on aprocess development substrate. In either case, the sensor 250 may beformed by forming a material stack that is the same material stack usedto formed active devices. The material stack may then be patterned witha patterning process (e.g., an etching process) that is substantiallysimilar to the patterning process being investigated for residualchemical reactions. In embodiments where the sensor 250 is formed on aproduction substrate 321, the sensor 250 may be formed in parallel withthe formation of active devices.

Referring now to operation 592, embodiments may include placing thesubstrate into a testing chamber 410, similar to the testing chamberdescribed above with respect to FIG. 4. In an embodiment, placing thesubstrate into a testing chamber may include attaching the probes 418 tothe probe pads 252 of the sensor 250.

Referring now to operation 593, embodiments may include executing adiagnostic procedure on the substrate. Embodiments may include anynumber of diagnostic procedures that may be useful in determining thepresence of residual chemical reactions, how residual chemical reactionschange over time, how residual chemical reactions respond to differentstimulus, or the like. According to an embodiment, process 590 mayinclude recoding electrical outputs from the sensor during thediagnostic procedure, as shown in operation 594.

Embodiments may include executing diagnostic procedures over any desiredtime period and under any desired environmental conditions. For example,the diagnostic procedures may be executed over a period of seconds,minutes, hours, days, weeks, etc. Additionally, the environmentalconditions may be altered to identify conditions that reduce oreliminate residual chemical reactions. For example, environmentalconditions, such as atmosphere (e.g., oxygen, inert gas, water vapor,etc.), pressure, temperature, or the like may be controlled during theexecution of the diagnostic procedure. In an embodiment, theenvironmental conditions may be held constant during the diagnosticprocedure, or the environmental conditions may be variable during theexecution of the diagnostic procedure.

In one embodiment, the presence of a residual chemical reaction may bedetermined by executing a diagnostic procedure that includes monitoringthe change in capacitance of a sensor 250. For example, if thecapacitance of a sensor increases over time, it may be indicative ofcorrosion occurring on the sensor 250. Alternatively, if the capacitanceof a sensor decreases over time, it may be indicative of residualetching of the sensor 250. Another indication of corrosion may be thepresence of a wide noise floor in the capacitance reading. In anotherembodiment, an increase in the leakage current may also be indicative ofcorrosion being present. In an embodiment, a decrease in the breakdownvoltage may be indicative of corrosion as well. With respect tobreakdown voltage decreases, it is proposed that corrosion resulting inthe presence of nodules on the surfaces of the sensor arms producelocalized increases in electric field that lead to field emission orcurrent arcing, and ultimately, in some instances, breakdown.

In an embodiment, the diagnostic procedure may include applying a singlefrequency to the probe pads in order to measure the behavior of thesensors 250. In additional embodiments, multiple frequencies may be usedto measure the behavior of the sensors 250 (e.g., the differentfrequencies may be applied to the sensor concurrently, or a frequencysweep may be applied to the sensor).

However, it is to be appreciated that some changes to the capacitance,breakdown voltage, current leakage, or the like may not be entirely dueto residual chemical reactions, such as corrosion. For example, residualetching byproducts may be a confounding factor that may need to beaccounted for in order to determine if a residual chemical reaction ispresent. Particularly, the residual etching byproducts may be moresusceptible to absorption, emission, thermal degradation, or the like.As these changes occur at the residual etch byproduct, the capacitances,breakdown voltages, and leakage current of the sensor may also change.Accordingly, embodiments include the integration of multiple sensorelements and diagnostic procedures that eliminate false positivesattributable to the presence of residual etch byproducts.

In one embodiment, the diagnostic procedure may include changing theenvironmental conditions, such as moisture in the atmosphere,temperature of the substrate, pressure of the atmosphere, or the like.In such embodiments, if the signal of interest (e.g., breakdown voltage,capacitance, leakage current, etc.) changes in response to theenvironmental condition, then the change may be indicative of thepresence of a residual etch byproduct instead of a residual chemicalreaction. Accordingly, embodiments provide a process for eliminatingfalse positives.

Referring now to operation 595, embodiments may include determining asubsequent processing operation based on the recorded electrical outputsfrom the sensor. For example, if excessive corrosion is present on thesensor, the subsequent processing operation may be to quench thesubstrate in order to minimize the corrosion. For example, the substratemay be quenched with a water vapor or any other reaction limiter. In anadditional embodiment, the subsequent processing operation may be tochange parameters of the etching process in order to minimize theresidual chemical reaction on subsequently processed substrates.

It is to be appreciated that the residual chemical reactions may besubstantially slow processes. For example, corrosion may proceed at arate that does not result in substantial damage to the device until daysor even weeks after the processing operation used to fabricate thedevice has been executed. Accordingly, embodiments may also include adiagnostic procedure that accelerates the residual chemical reactions.In one embodiment, executing the diagnostic procedure may includeapplying a stimulus to the sensor in order to accelerate the residualchemical reaction. For example, a bias voltage may be applied to theprobe pads of the sensor. In an embodiment, a bias voltage ofapproximately 25 V or more, 50 V or more, or 75 V or more may be appliedto the probe pads in order to accelerate the residual chemical reaction.In such embodiments, a determination of the presence and extent of theresidual chemical reaction may be determined in minutes or hours insteadof days or weeks,

Such voltage bias acceleration diagnostic procedures may be particularlybeneficial when used on device substrates. For example, a device may befabricated and the voltage bias acceleration diagnostic procedure may beimplemented on a sensor immediately following the fabrication of thedevice. If the sensor reports that the resulting residual chemicalreactions are below a desired threshold, then the substrate may continueon to subsequent processing without needing to worry about subsequentresidual chemical reactions damaging the final device. Alternatively, itthe sensor reports that the resulting residual chemical reactions arebelow a desired threshold, then the substrate may be reworked, processedfurther to mitigate the effect of residual chemical reactions (e.g.,quenching, etc.), or the substrate may be scrapped. Accordingly, asubstrate that includes devices that will ultimately fail or be damagedwill not continue on in the fabrication process, and overall yield maybe increased.

While voltage bias acceleration diagnostic procedures is particularlybeneficial for use on production substrates, it is to be appreciatedthat process development substrates also benefit from voltage biasacceleration diagnostic procedures. For example, the speed of processdevelopment may be increased since wait times to determine the presencesand extent of residual chemical reactions may be reduced.

In addition to voltage being used as an accelerant, embodiments includemany other accelerants that may be used. In one embodiment, moisture,dielectric fluids, engineered fluids (e.g., ions, acids, bases, PH),heat, gases, plasma induced ionic species, or the like may be used toaccelerate a residual chemical reaction. In an embodiment, theaccelerants may be formed over the sensor as a coating. Additionalembodiments may include exposing the sensor to the accelerant (e.g., theaccelerant is in the atmosphere surrounding the sensor, the accelerantis sprayed or otherwise deposited over the sensor, or the like. Thechoice of which accelerant to use may be dependent on the materials thatare being processes, the processing operations being investigated, orthe residual chemical reactions that are being investigated.

Referring now to FIG. 6, a block diagram of an exemplary computer system660 of a processing tool is illustrated in accordance with anembodiment. In an embodiment, computer system 660 is coupled to andcontrols processing in the processing tool. Computer system 660 may beconnected (e.g., networked) to other machines in a Local Area Network(LAN), an intranet, an extranet, or the Internet. Computer system 660may operate in the capacity of a server or a client machine in aclient-server network environment, or as a peer machine in apeer-to-peer (or distributed) network environment. Computer system 660may be a personal computer (PC), a tablet PC, a set-top box (STB), aPersonal Digital Assistant (PDA), a cellular telephone, a web appliance,a server, a network router, switch or bridge, or any machine capable ofexecuting a set of instructions (sequential or otherwise) that specifyactions to be taken by that machine. Further, while only a singlemachine is illustrated for computer system 660, the term “machine” shallalso be taken to include any collection of machines (e.g., computers)that individually or jointly execute a set (or multiple sets) ofinstructions to perform any one or more of the methodologies describedherein.

Computer system 660 may include a computer program product, or software622, having a non-transitory machine-readable medium having storedthereon instructions, which may be used to program computer system 660(or other electronic devices) to perform a process according toembodiments. A machine-readable medium includes any mechanism forstoring or transmitting information in a form readable by a machine(e.g., a computer). For example, a machine-readable (e.g.,computer-readable) medium includes a machine (e.g., a computer) readablestorage medium (e.g., read only memory (“ROM”), random access memory(“RAM”), magnetic disk storage media, optical storage media, flashmemory devices, etc.), a machine (e.g., computer) readable transmissionmedium (electrical, optical, acoustical or other form of propagatedsignals (e.g., infrared signals, digital signals, etc.)), etc.

In an embodiment, computer system 660 includes a system processor 602, amain memory 604 (e.g., read-only memory (ROM), flash memory, dynamicrandom access memory (DRAM) such as synchronous DRAM (SDRAM) or RambusDRAM (RDRAM), etc.), a static memory 606 (e.g., flash memory, staticrandom access memory (SRAM), etc.), and a secondary memory 618 (e.g., adata storage device), which communicate with each other via a bus 630.

System processor 602 represents one or more general-purpose processingdevices such as a microsystem processor, central processing unit, or thelike. More particularly, the system processor may be a complexinstruction set computing (CISC) microsystem processor, reducedinstruction set computing (RISC) microsystem processor, very longinstruction word (VLIW) microsystem processor, a system processorimplementing other instruction sets, or system processors implementing acombination of instruction sets. System processor 602 may also be one ormore special-purpose processing devices such as an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA), adigital signal system processor (DSP), network system processor, or thelike. System processor 602 is configured to execute the processing logic626 for performing the operations described herein.

The computer system 660 may further include a system network interfacedevice 608 for communicating with other devices or machines. Thecomputer system 660 may also include a video display unit 610 (e.g., aliquid crystal display (LCD), a light emitting diode display (LED), or acathode ray tube (CRT)), an alphanumeric input device 612 (e.g., akeyboard), a cursor control device 614 (e.g., a mouse), and a signalgeneration device 616 (e.g., a speaker).

The secondary memory 618 may include a machine-accessible storage medium631 (or more specifically a computer-readable storage medium) on whichis stored one or more sets of instructions (e.g., software 622)embodying any one or more of the methodologies or functions describedherein. The software 622 may also reside, completely or at leastpartially, within the main memory 604 and/or within the system processor602 during execution thereof by the computer system 660, the main memory604 and the system processor 602 also constituting machine-readablestorage media. The software 622 may further be transmitted or receivedover a network 620 via the system network interface device 608.

While the machine-accessible storage medium 631 is shown in an exemplaryembodiment to be a single medium, the term “machine-readable storagemedium” should be taken to include a single medium or multiple media(e.g., a centralized or distributed database, and/or associated cachesand servers) that store the one or more sets of instructions. The term“machine-readable storage medium” shall also be taken to include anymedium that is capable of storing or encoding a set of instructions forexecution by the machine and that cause the machine to perform any oneor more of the methodologies. The term “machine-readable storage medium”shall accordingly be taken to include, but not be limited to,solid-state memories, and optical and magnetic media.

In the foregoing specification, specific exemplary embodiments have beendescribed. It will be evident that various modifications may be madethereto without departing from the scope of the following claims. Thespecification and drawings are, accordingly, to be regarded in anillustrative sense rather than a restrictive sense.

What is claimed is:
 1. A method for determining the presence of residualchemical reactions, comprising: forming a sensor on a substrate, whereinforming the sensor comprises: forming a material stack over thesubstrate; and forming a first electrode and a second electrode in thematerial stack, wherein each of the first electrode and the secondelectrode has a sidewall that extends an entire height of the materialstack; placing the substrate in a testing chamber; executing adiagnostic procedure on the substrate, wherein electrical outputs fromthe sensor are recorded during the diagnostic procedure; and determininga subsequent processing operation based on the recorded electric outputsfrom the sensor.
 2. The method of claim 1, wherein the substrate is adevice substrate, and wherein the sensor is formed in a scribe line ofthe device substrate.
 3. The method of claim 2, wherein the sensor isformed in parallel with the active devices on the device substrate, andwherein the sensor includes the same materials as the active devices. 4.The method of claim 1, wherein the substrate is a process developmentsubstrate.
 5. The method of claim 1, wherein the diagnostic procedureincludes monitoring changes to a capacitance.
 6. The method of claim 5,wherein the diagnostic procedure includes applying a single frequency tothe sensor.
 7. The method of claim 5, wherein the diagnostic procedureincludes applying a plurality of frequencies to the sensor.
 8. Themethod of claim 7, wherein the plurality of frequencies are applied as afrequency sweep.
 9. The method of claim 1, wherein the diagnosticprocedure includes varying environmental conditions during thediagnostic procedure.
 10. The method of claim 9, wherein theenvironmental conditions include pressure.
 11. The method of claim 1,wherein the diagnostic procedure includes a voltage bias accelerationdiagnostic procedure.
 12. The method of claim 11, wherein the subsequentprocessing operation includes approving the substrate for continuedprocessing when a residual chemical reaction effect is below a thresholdvalue.
 13. The method of claim 11, wherein the subsequent processingoperation includes reworking the substrate or scrapping the substratewhen a residual chemical reaction effect is above a threshold value.